We consider a gmp model as the PA with nonlinear orders \(K_a=K_b=K_c=7\) , memory lengths \(L_a=L_b=Lc=3\) , and cross-term lengths \(M_b=M_c=1\)  [1]}. The corresponding parameters are estimated from the measurements of the RF WebLabThe RF WebLab is a PA measurement setup that can be remotely accessed at www.dpdcompetition.com. using the ILA and a 55 MHz signal. The measured saturation point and measurement noise standard deviation of the PA are \(20.9\)  V (\(\approx 36.4\)  dBm) and \(0.053\)  V. We consider a 50 \(\Omega \)  load impedance. The remaining parameters are given in Table REF . The number of training messages in \(m\)  for each batch is \(N=1024\) . The optimizer for gradient descent is Adam [2]} with a learning rate \(0.001\) . The messages are mapped to a sequence of symbols \(u^{\text{sym}}\)  according to a \(M=64\)  qam constellation. The sampling rate is 200 MHz, with upsampling and downsampling rate \(R=4\) . The pulse shaping filter is a rrc filter with a roll-off factor \(0.1\) , so the bandwidth of the baseband signal \(u\)  is 55 MHz. The papr of the signal is \(10.3\)  dB, which is similar to that of an ofdm signal. We set \(G=3\)  in (REF ), and the perturbation variance \(\sigma ^2_{\pi }=0.08\) . We consider an awgn channel with fixed noise standard deviation \(\sigma _{\text{ch}}=0.3\)  Volt. We consider a simulated ADC in the feedback path of the ILA with infinite resolution but three different sampling rates \(F_s^{\text{ADC}}=110\)  MHz, 220 MHz, and 550 MHz (referred to full-rate ADC). Note that \(F_s^{\text{ADC}}\)  needs to be larger than the Nyquist rate (110 MHz) of the distortion-free 55 MHz signal to capture the out-of-band behavior of the PA output signal.
